1. Field of the Invention
The present invention relates to speaker systems and, more particularly, to a cabinet construction for a front-loaded-horn type speaker system.
2. Description of the Related Art
A front-loaded-horn type speaker system (hereinafter referred to as FLH) is known as one of conventional techniques to boost a low-frequency range of a speaker system. The FLH is a speaker system provided with a horn in front of a speaker unit. The FLH has a feature in that a sound pressure at a low-frequency range can be increased since a sufficiently large load can be accepted at the low-frequency range. Additionally, the FLH is capable of reproducing a bright bass sound with a superior transition characteristic.
However, the FLH has the following drawbacks.
(1) A speaker system becomes extremely large when a cutoff frequency indicating a bass limit is lowered so as to extend an overall sound range, which is not practical for home use.
(2) In order to reduce the size of a horn, a folded horn having a folded middle portion has been developed. However, such a folded horn has a complex construction and is not suitable for mass production, and, thus, a manufacturing cost must be increased.
(3) Since the folded horn is formed by connecting straight sound passages, deterioration of sound quality can not be prevented due to undesired resonance in a straight portion or disturbance of air current at a folded portion.
As mentioned above, although the conventional FLH has superior features, there are many drawbacks and, thus, the FLH has not become popular.
The present inventor suggested in U.S. Pat. No. 5,824,969 an improved speaker system which is related to a back-loaded-horn type speaker system (hereinafter referred to as BLH). This speaker system is constructed so a sound radiated from a back of a speaker unit exits outside after passing through a three-dimensional spiral sound passage formed by a coaxial dual-tube structure and a spiral partition plate provided in a gap formed within the coaxial dual-tube. Thus-constructed improved BLH can be compact and creates a high-fidelity sound. However, this system is not capable of creating a heavy bass sound since a load cannot be applied to a diaphragm at a frequency below 30 Hz.